Acoustic Cavitation at the Water-Glass Interface

Power ultrasound (20 kHz, I-ac = 20-56 W cm(-2)) was used to investigate physical and chemical effects of acoustic cavitation at the water-glass interface. Physical effects were characterized with different techniques of microscopy (optical, SEM, AFM) and were shown to increase and evolve as a function of sonication duration according to two distinctive periods: (i) an incubation period that initiates weak points on a glass surface, which may be the result of acoustically created shock-waves, and (ii) a second period of erosion, which is related to direct impact fracture erosion of the material. Chemical analysis of water (ICP-OES), after ultrasonic treatment, clearly indicates that bubble collapse at the water-glass interface initiates not only mechanical erosion but also accelerates the leaching processes of the glass components.